Loud-speaker



Feb. 3, 1942. J SEABERT 2,271,525

LOUD-SPEAKER Filed March 30, 1940 Patented Feb. 3, 1942 LOUD-SPEAKER John Dale Seabert, Indianapolis, Ind., assignor I to Radio Corporation .of America, a corpora- J I tion of Delaware Application March '30, 1940, Serial No. 326,877

9 Claims.

This invention relates to electrodynamic sound translating apparatus, and more particularly to' the structure of the voice coil form and windings thereof.

In recent years, sound translating devices, such as loudspeakers, have been provided with two or more voice coils at least one of which is particularly effective at low frequencies and another of which is particularly effective at high frequencies. These voice coils or windings are wound on a coil form which has an annular bead or compliance formed circumferentially thereon at some suitable point intermediate its ends, one of the windings being on one side of the coinpliance and the other winding being on the other side of the compliance. A construction of this sort necessitatesbringing the leads from one of 179-.-.115.5) so that the two sections are electrically insulated from each other. At the endof the corrugation or beadin one of the sections, I provide one notch; and at the diametrically opposite end of the other of said form sections,- I provide a similar notch, preferably also in the-corrugation thereof. Thus, the complete form has two notches formed in the corrugation at diametrically opposite points. The two voice coils are wound, as before, one on each side of the corrugation, and' they are preferably connected in series. The lead common to both of the coils or windings is formed with a bend therein which is inserted into one of said notches during manufacture, and

the coils across the bead or corrugation. If these is found that they break after a comparatively leads are made taut, as has beenthe practice, it

short period of use because, when the high frequency coil alone is effective, only that part of ,the coil form on which the high frequency coil is wound will move, the corrugation or compliance yielding to permit such movement. Since the leads which cross the corrugation are taut, they cannot yield similarly to the compliance, and they are forced to thin out and eventually burn out because of the reduced cross-section therein,

or they may yield and break because they lack the requisite tensile strength tostand up under A this treatment.

The primary object of my present invention is to provide an improved voice coil form and voice coil winding structure which will be free from the aforementioned disadvantages.

More particularly, it is an object of my present the other or terminal lead from one of the windings (for example, the low frequency winding) is brought up over the corrugation and is also formed with abend therein which is located in the other of said notches. Thus, due to the flexibility of the conductive wire of which the voice coils are made, the bends in the aforesaid notches can yield more or less as the high frequency coil is effective to cause only its portion of the coil form to vibrate.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and invention to provide, in a sound translating device of the electrqdynamic type, a voice coil form and winding structure of the type set forth which will stand up under ordinary conditions of use and which will have a long life.

Another object of my present invention is to provide, in a voice coil form and winding structure of the type mentioned, a novel method of bringing out the leads of the double voice coil to reduce breakage of the leads in service to a minimum.

It. is also an object of my present invention to provide an improved voicecoil form and winding,

structure as aforesaid which is simple in construction, which readily lends itselfto large quantity manufacture, and which is highly efficient in use.

. In accordance with my present invention, I

make the voice coil-form of two substantially semi-cylindrical sections, each provided with a bead or corrugation which acts as a compliance.

The two form sections are preferably made of an electrically conductive material and are spaced method of operation, as well as additional objects and advantages thereof, will best .be understoodfrom the following description of two embodiments thereof, when read in connection with the accompanying drawing in which Figure 1 is anelevation of a voice coil form and winding structure in accordance with one form of my invention,

Figure 2 is an enlarged central sectional view thereof, l

Figure 3 is an exploded perspective view of this form of my invention, and

Figure 4 is a fragmentary detail view of another form of my invention.

l'teferring more particularly to the drawing, wherein similar reference numerals designate corresponding parts throughout, there is shown a diaphragm or other vibratile member I to which is, secured, in well-known manner, a voice coil form 5 having a circumferential corrugation 5 thereon at some suitable point intermediate its ends which acts as a compliance between the portions of the form 3 on either side thereof. On one side of the corrugation or compliance 5 is a low frequency winding 1 and on the other side of the compliance 5 is-a high frequency winding 9.

ill

I slightly from each other at their adjacent ends- The voice coil form 3 is formed of two semicylindrical halves or sections 3a and 3b, as clear- 1y shown in Fig. 3, each section being formed with half of. the corrugation'5. The two form sections 3a .and 3b may be held together by being cemented to the skirt la of the nonconductive diaphragm l, and they are spaced apart from are electrically insulated from each other.

each other at their adjacent ends so that they At one end of the section 3a, a portion of the material thereof is removed, preferably at the corrugation, to provide-a notch I3, and a similar notch I5 is provided in the diametrically opposite end of the corrugation in the other section 3b.

carried by said form on one side of said com pliance, said windinghaving a lead crossing said compliance and said lead also having a compliance comprising a bend therein adjacent the The low frequency winding ,1 terminates in a lead I! which is formedwith a reverse or any other suitable bend or loop Ila located in the notch l5 and arranged to lie in the plane of the coils l and 9 (that is, of course, in aplane which is substantially tangent to the coils l and 9 at the notch l5)- Similarly, the common lead 19 between the coils l and 9 is formed with a reverse or other suitable bend or loop i9a which is 'located in the notch i3, as clearly shown in Fig, 2. It will be seen, from the foregoing, that with my improved construction the leads i1 and Hi can readily yield at their respective loops or bends Ila and Illa when the assembled voice coil form 3 yields at the corrugation 5 in response to the signal energy in the high frequency coil.9, and therefore the leads I? and i9 will not break down. By nesting the loops or bends Ila and liia in the notches l5 and I3, respectively, to lie in the plane of the windings i and 9 in each case, the loops or bends will not catch on the pole structure and will not interfere with the operation of the vibrating structure in any way.

In Fig. 4, I have shown a somewhat modified form of the invention which, while satisfactory, is not as preferable as the previously described modification. In the modification of Fig. 4, the lead I! is illustrated as having its bend l'la formed into the corrugation 5 so that, like the first described modification, the bend Ila lies adjacent the compliance. The bend l9a in the common lead i9 may, of course, be formed similarly. form 3 may be made of a single cylindrical piece In this form of my invention, the coil iii - compliance in said voice coil form, said bend being located in said notch whereby said bend lies substantially along said first named compliance and substantially in the plane of said winding. 5. In an electrodynamic sound translating device, the combination of a voice coil form having a circumferential corrugation therein constitutin conventional manner. Where, however, the voice coil form 3 is made in two sections, as previously described, and these two sections are electrically insulated from each other, the lead 11 may be soldered to one of the sections (for example, the section 3b), and either the common lead l9 or the terminal lead 2! fromfthe high frequency coil 9 may be connected to the other section 3a, in which case the two form sections 3a and 3b may be availed of as terminals to facilitate bringing out the leads from the two coils.

Although I have shown and described but two embodiments of my invention, I am fully aware that many other modifications thereof, as well as changes in the modifications described, are possible, Accordingly, I desire it to be underexcept insofar as is made necessary by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. In an electrodynamic sound translating device, the combination of a voice coil form having a compliance therein, and at least one 'conductive winding carried by said coil form on one side of said compliance, said winding having a stood that I do not wish to limit my inventionjj 3. In an electrodynamic sound translating device, the combination of a voice coil form having a compliance therein, and a conductive winding ing a compliance-between the portions of said form on either side of said corrugation, a portion of said form being removed at one point in said corrugation to provide a notch therein, and a conductive winding carried by said form on one side of said corrugation, said winding having a lead crossing said corrugation and said lead also having a compliance comprising a bend therein adjacent the compliance in said voice coil form,

said bend being located in said notch whereby said bend lies substantially along said corrugation and substantially in the. plane of said winding.

6. The invention set forth in claim 4 char acterized in that said voice coil form is constituted by two substantially semi-cylindrical sections connected together, and characterized' further in that said notch is formed in the end of one of said sections.

7. In an electrodynamic sound translating device, the combination of a voice coil form havinga circumferential corrugation therein constituting a compliance between the portions of said formon either side of said corrugation, said form being-provided with a pair of notches therein at substantially diametrically opposite points on said, corrugation, a pair of windings carried by said form one on each side of said corrugation, said windings having a common lead formed with a bend therein, said bend lying in one of said I notches, and at least one of said windings having a lead crossing said corrugation, said last-named lead also having a bend therein and said last-'- named bend lying in the other of said notches.

8. The invention set forth in claim '7 characterized in that said voice coil form is constituted by two substantially semi-cylindrical sections connected together, characterized further in that one of said notches is formed in the end of one of said sections, and characterized still further in that. the other of said notches is formed in the diametrically opposite end of the other of said sections.

9. The invention set forth in claim 7 char-. acterized in that said voice coil form is con stituted by two substantially semi-cylindrical sections made of a conductive material, said sections being connected together by a nonconductive means whereby said sections are electrically insulated from each other.

JOHN DALE SEABERT. I 

